The "Deutscher Wetterdienst" (DWD) provides current severe weather warnings as a JSON file (http://www.dwd.de/DWD/warnungen/warnapp/json/warnings.json). To be able to filter and evaluate these according to your own region, you need to know the 9 digit WarnCellID of your home town. It can be found here. A click on the WarnCellID will display the current weather warnings for the selected region.
If no warning is found (although the weather outside makes it most likely), it is advisable to search for the parent region. An example: If the query of 801053100 (city of Ratzeburg) does not return a result, try 101053000 (duchy of Lauenburg district) instead. This procedure usually leads to a hit. The link at the top of the browser can then be saved permanently, thus saving you from having to search for "your" WarnCellID again.